Known automotive gas turbines of conventional design, having a free power turbine as a last stage, will encounter several difficulties. The auxiliaries of the plant are preferably driven from the gasifier portion in order to permit the power turbine to produce a full starting torque (about 2:1), and also to dispense with the torque converter in an automatic gear box (usually a torque converter+three ratios forward and one ratio reverse in an ordinary car) and the corresponding losses and costs. By adding the auxiliary drive to the gasifier portion the latter will have a slow acceleration performance, or will suffer from over-temperatures, meaning an increased fuel consumption and problems concerning exhaust gas emissions (NOx) and useful lifetime (hot components). In order to meet such troubles the hydraulic torque converter has been re-introduced, and it will then have to take care of the full output torque. In such manner the auxiliaries may be driven from the power turbine, which will always rotate when the plant is operating, and which drives the pump in the hydraulic torque converter. That will, however, imply extra losses. In order to reduce those a direct clutch (lock-up) has been introduced in the hydraulic torque converter, which at high speed locks the torque converter and eliminates its slip losses. Practical use has, however, shown that this "lock-up" is easily forgotten, and also with consideration to the driving the auxiliaries is used during very high speed only, which means that part-load fuel consumption will be high. This is especially noticeable during stall, when the power turbine speed increases and the torque ratio is reduced from 2:1 to about 1,5:1, which must be compensated by the torque converter.
The present invention aims at solving the problem, above referred to, by proposing a combined turbine-transmission system, which permits the output shaft being braked to standstill, without the speed of the power turbine being reduced to below that necessary for operating the auxiliaries. This is obtainable by means of the system without any hydraulic or other slipping member being used for the (full) torque of the plant, while simultaneously means are provided for obtaining a continuous variation of gear exchange ratio.